Classifications

• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
  • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
  • C21D8/0226—Hot rolling
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
  • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D6/00—Heat treatment of ferrous alloys
  • C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
  • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
  • C21D8/0236—Cold rolling
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
  • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
  • C21D8/0273—Final recrystallisation annealing
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
  • C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
  • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
  • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D2211/00—Microstructure comprising significant phases
  • C21D2211/001—Austenite
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D2211/00—Microstructure comprising significant phases
  • C21D2211/008—Martensite

Definitions

• the present invention relates to a stainless steel plate and a method for producing the same. More specifically, a stainless steel plate excellent in corrosion resistance and shape flatness, having a sufficiently fine crystal grain suitable for etching processing and laser processing that require recent precision, and suitable for precision processing, and its It relates to a manufacturing method.
• This application claims priority based on Japanese Patent Application No. 2012-194214 for which it applied to Japan on September 4, 2012, and uses the content here.
• stainless steel plates with fine crystal grains are suitable for fine processing such as photoetching and laser cutting.
• Examples of such stainless steel plates include the following.
• Patent Document 1 C: 0.03% or less, Si: 1.0% or less, Mn: 2.0% or less, P: 0.1% or less, Ni: 4.0% or more and 20.0% or less Cr: 12.0% or more and 25.0% or less, N: 0.20% or less, and Nb: 0.01% or more and 0.3% or less, with the balance being Fe and impurities, average
• a stainless steel plate for photoetching with a crystal grain size of 15 ⁇ m or less and a method for producing the same are disclosed.
• Patent Document 2 as described above, C: 0.08% or less, Si: 1.0% or less, Mn: 2.0% or less, P: 0.045% or less, S: 0.05% or less, Ni: 5.0% or more and 15% or less, Cr: 15% or more and 20% or less, and the balance is made of Fe and inevitable impurities, and the average crystal grain size is 15 ⁇ m or less.
• the manufacturing method is disclosed.
• Patent Documents 3 and 4 disclose a stainless steel plate for photoetching.
• metastable austenitic stainless steel is used, work strain is introduced by cold rolling and work-induced martensitic transformation is promoted, and reverse transformation to austenitic structure is performed at a relatively low temperature. Is known to be effective.
• SUS301 and SUS301L which have low austenite stability and are easy to process-induced martensite transformation, are known as component systems that are relatively easy to refine. These steel plates have been put to practical use in automobile cylinder head gaskets and diaphragm plates for diaphragm compressors. Or the material refined as a base material for photo-etching processing or laser processing is put into practical use.
• the average crystal grain size is 6, 7, 8, 15 ⁇ m.
• the average crystal grain size is 7, 8 ⁇ m.
• the average crystal grain size is 6, 7, and 9 ⁇ m.
• alloy B in Table 2 of Patent Document 4 the average crystal grain size is 6, 9 ⁇ m.
• the conventional stainless steel plate containing 18% or more of Cr and 8% or more of Ni has a problem that the average crystal grain size is too coarse to be used in recent highly integrated metal mask applications. there were.
• the average crystal grain size satisfying 5 ⁇ m or less is a composition range inferior in corrosion resistance of Cr: less than 18% and Ni: less than 8%.
• an average crystal grain size of a stainless steel plate excellent in corrosion resistance containing 18% or more of Cr and 8% or more of Ni should be 5 ⁇ m or less. Can be confirmed to be difficult.
• Patent Documents 1 to 4 described above have the following description as rolling reduction ratios before grain refinement annealing.
• the rolling reduction during cold rolling before the final annealing is not particularly limited and may be a rolling reduction of about 40% or more that is normally performed”. Also, in this document, the experimental conditions for laboratory examples are described in [Table 2]. However, the rolling reduction before annealing is 50% in 13 cases out of 14 cases, and 65% in only one case.
• Claim 3 of Patent Document 4 states that “after cold rolling at a rolling rate of 30% or more, heat treatment is performed at a temperature of 700 ° C. or more and 900 ° C. or less to make the average crystal grain size 10 ⁇ m or less”. Has been. Also, paragraph [0026] of the same document states that “If the rolling rate is less than 30%, sufficient strain that becomes a driving force for recrystallization does not occur, and a mixed grain structure is formed in the subsequent heat treatment, and the etched surface becomes rough. Therefore, the rolling ratio is set to 30% or more. " As described above, this document confirms that the rolling rate is as low as about 30%.
• paragraphs [0030] to [0032] of the same document describe that, as an example, after cold rolling from 2.5 mm thickness to 1 mm thickness, fine grain annealing was performed at low temperature.
• the rolling rate at this time is only 60%.
• Patent Document 3 describes the rolling reduction before the fine grain annealing as in Patent Document 4. However, there is no description that the reduction rate before the grain refinement annealing contributes to the promotion of the grain refinement, and the condition of a very low reduction rate that only requires recrystallization.
• Patent Document 2 does not describe the influence of the rolling reduction before grain refinement annealing on the average crystal grain size after grain refinement annealing. In the example of this document, only 60% of cases rolled from 2.5 mm to 1 mm are described.
• Patent Document 7 and Patent Document 8 have been reported for the adverse effect of the oxide film formed on the stainless steel plate during the bright annealing on the etching processability.
• JP 2003-3244 A Japanese Patent Application Laid-Open No. 2005-314772 JP 2005-320586 A JP 2005-320587 A JP 2009-299171 A JP 2011-1117024 A JP 2002-275541 A JP-A-11-269613
• stainless steel sheets with a product thickness of 150 ⁇ m or less are frequently used in precision machining applications, but it is more difficult to secure a large rolling reduction with such thin sheet thickness, and it is not flat. Since it is difficult to correct the shape with a tension leveler or the like, a solution has been desired.
• the present invention has been made in view of the above situation, and in order to ensure corrosion resistance equivalent to or higher than that of SUS304 that is generally used, it contains 18% or more of Cr and 8% or more of Ni, while maintaining an average.
• An object is to provide a stainless steel plate suitable for precision machining with a crystal grain size of 5 ⁇ m or less.
• the present inventors paid attention to the fact that the amount of C greatly affects the hardness of the generated martensite structure, and adjusted the component system so as to reduce the amount of C added. Furthermore, the amount of Nb added, which is highly effective in suppressing crystal grain growth, was optimized.
• the present invention based on the above findings is as follows. [1] % By mass, C ⁇ 0.030%, Si ⁇ 0.80%, Mn ⁇ 1.20%, P ⁇ 0.045%, S ⁇ 0.01%, Cu ⁇ 0.60%, Mo ⁇ 0. 60%, Al ⁇ 0.02%, 18.0% ⁇ Cr ⁇ 19.0%, 8.0% ⁇ Ni ⁇ 9.0%, 0.03% ⁇ Nb ⁇ 0.12%, 0.02% ⁇ N ⁇ 0.1%, the balance consists of iron and impurities,
• the Md30 value defined by the formula (1) is 25 to 55, A stainless steel plate having an average crystal grain size of 5 ⁇ m or less.
• the present invention can sufficiently promote the work-induced martensite transformation without carrying out special cold rolling by reviewing all the composition ranges forming the alloy in detail and controlling them to an appropriate range.
• a stainless steel plate suitable for metastable austenitic precision machining with excellent workability, rollability and shape flatness after rolling, suitable for crystal grain refinement, and excellent corrosion resistance is realized.
• the effect of the present invention is remarkable when the thickness tolerance of variation such as thickness is small and the thickness of the product, which is difficult to correct the product shape, is 150 ⁇ m or less.
• C content strongly enhances austenite stability and suppresses martensitic transformation, remarkably increases the strength of the transformed martensite structure, and lowers rolling workability. Therefore, the upper limit of C is limited to 0.030%.
• C produces chromium carbide when annealed at a low temperature, and lowers the corrosion resistance. It also makes the recrystallization behavior unstable. Therefore, it is preferable that it is 0.025% or less. Although there is no particular lower limit, it is 0.003% or more in normal production.
• the upper limit of Si is set to 0.80%. If there is no problem such as insufficient deoxidation in the production process, it is preferably 0.7% or less. Although there is no particular lower limit, it is usually 0.10% or more.
• Mn is an austenite generating element and lowers the Md value. Therefore, the upper limit of Mn is 1.20%.
• a large amount of Mn is preferably 1.0% or less in order to reduce the corrosion resistance. Although there is no particular lower limit, it is preferably 0.30% or more because it also contributes to the strength of the steel.
• the amount of P that impairs hot workability is preferably small, and the upper limit is 0.045%.
• the amount of S that impairs hot workability is preferably small, and the upper limit is 0.01%. More preferably, it is 0.007% or less.
• Cu is an austenite generating element and lowers the Md value. Therefore, the upper limit of Cu is set to 0.60%. It is preferable that it is 0.5% or less. Although a lower limit is not particularly provided, it may be contained by 0.05% or more by bringing in from a scrap raw material or the like.
• ⁇ 18.0% ⁇ Cr ⁇ 19.0% Cr is required to be 18.0% or more from the viewpoint of corrosion resistance. From the viewpoint of increasing the Md value, the upper limit of Cr is 19.0%. From the balance between corrosion resistance and cost, it is preferably 18.5% or less.
• Ni is required to be 8.0% or more from the viewpoint of corrosion resistance. From the viewpoint of increasing the Md value, the upper limit of Ni is limited to 9.0%. Ni increases the austenite stability and is an expensive element, so it is preferably 8.5% or less.
• Mo limits the upper limit to 0.60% from the viewpoint of increasing the Md value. Since Mo is an expensive material, its content is preferably 0.50% or less. Although there is no particular lower limit, 0.05% or more is effective because it contributes to the improvement of corrosion resistance.
• Nb is an indispensable element for suppressing the growth of crystal grains and promoting the refinement, and it is essential to contain more than 0.03%. If it is 0.03% or less, these sufficient effects cannot be exhibited.
• the chemical composition of the present invention is less likely to be finer than the 301L system, it is preferable to contain more than 0.05% Nb. Excess content not only causes an increase in cost, but also inhibits recrystallization, so the upper limit is made 0.12%. In order to ensure a stable recrystallization behavior, the content is preferably 0.10% or less.
• N like C, greatly increases the austenite stability, so its upper limit is limited to 0.1%. N lowers the rollability in hot rolling and increases surface scratches, so 0.08% or less is preferable. However, 0.02% or more is added because it contributes to improving the strength of the steel by solid solution strengthening. From the viewpoint of improving the strength, addition of 0.03% or more is preferable.
• the upper limit of Al is 0.02%. Preferably, it is 0.015% or less.
• Al will reduce diffusion bonding property, and in such a use, it is preferable to set it as 0.01% or less. More preferably, it is 0.008% or less.
• the lower limit is not particularly set, even when no intentional addition is performed and Al is not used as a deoxidizer, it is often contained in an amount of about 0.001%.
• Md30 value 25-55
• the Md30 value indicating the stability of the austenite structure is a value obtained from the chemical composition of steel by the equation (1) (Gladman's equation).
• the Md30 value means the temperature at which 50% martensitic transformation occurs when 30% strain is applied. The higher the Md30 value, the more martensitic transformation is promoted, and the finer graining by reverse transformation becomes easier.
• the Md30 value that can realize an average crystal grain size of 5 ⁇ m or less is not limited to 25 or more, without performing cold rolling with special cooling or cold rolling with significantly multiple passes. From the viewpoint of promoting martensitic transformation, the Md30 value is preferably 28 or more, and more preferably 30 or more. On the other hand, when Md30 is high and the stability of austenite is low, work hardening during cold rolling is large and the rolling load is large, so the upper limit is 55.
• the Md30 value is preferably 48 or less, more preferably 40 or less. It is.
• ⁇ Average crystal grain size ⁇ 5 ⁇ m The average grain size is limited to 5 ⁇ m or less. The reason for the limitation is shown below. It is known that the etched surface and the laser processed surface are affected by the crystal grain size, and the smoother the processed surface, the finer the particle. In recent high performance metal masks, stainless steel plates with a thickness of 150 ⁇ m to 80 ⁇ m are mainly used. For materials provided for high-performance metal masks and precision etching applications, a thickness accuracy of ⁇ 4% is guaranteed, and variations in the thickness of actual products are generally within ⁇ 3%. .
• the plate thickness accuracy of ⁇ 3.2 to 6.0 ⁇ m is guaranteed, and the actual product is limited to plate thickness variations of ⁇ 2.4 to 4.5 ⁇ m. is there.
• the average crystal grain size is preferably 4.5 ⁇ m or less.
• the average crystal grain size is more preferably 3.0 ⁇ m or less.
• the stainless steel sheet of the present invention is effective in applications that require corrosion resistance and refinement of crystal grains other than precision processing applications.
• applications include applications where fatigue strength is expected to be improved by refining crystal grains (for example, diaphragm plates for cylinder head gasket diaphragm type compressors for automobiles) or cases where surface roughening does not occur after molding.
• Preferable uses equipment parts such as a stainless steel housing, a mechanical chassis, or a toner blade of a printing apparatus can be mentioned.
• the manufacturing method of the stainless steel plate of this invention is demonstrated.
• the raw material is melted so as to have a predetermined chemical composition, and a static casting or continuous casting is hot-rolled and annealed. Thereafter, the hot-rolled steel sheet from which the oxide scale on the surface is removed is cold-rolled at a predetermined rolling rate and annealed at a predetermined temperature.
• a hot rolled coil as a base material is required to have excellent flatness.
• a plate thickness deviation sheet crown
• the rolling is such that only one side is stretched and the stable rolling becomes difficult.
• a 600 mm wide hot rolled coil is employed from the beginning, cold rolling becomes stable and it is relatively easy to ensure a large reduction ratio.
• a rolling reduction exceeding 65% is essential from the viewpoint of promoting the processing-induced martensitic transformation and introducing sufficient processing strain. From the viewpoint of reducing the grain size after annealing, the higher the rolling reduction, the better.
• a rolling reduction of more than 70% is preferable in order to stably realize fine graining even if there is manufacturing variation during mass production. If the rolling shape does not deteriorate during cold rolling, it is more preferable to set the rolling reduction to 75% or more.
• the thickness before cold rolling is generally 300 ⁇ m or less, and a large reduction ratio is ensured due to the fact that the thickness of the rolled material is thin relative to the work roll diameter. Is particularly difficult.
• the hardness increase of the transformed martensite structure is suppressed, and even the component system in which martensitic transformation is likely to proceed is reduced.
• cold rolling exceeding 70% can be stably performed.
• the upper limit of the rolling reduction is not particularly defined, but is usually 90% or less because the hardness of the material increases with rolling, making rolling difficult.
• -Annealing temperature 810-940 ° C If the annealing temperature is high, crystal grains grow and become coarse, so the upper limit of the annealing temperature is 940 ° C. From the viewpoint of preventing grain growth, 900 ° C. or lower is preferable. In order to make the average particle size 3 ⁇ m or less, 875 ° C. or less is preferable. On the other hand, if the annealing temperature is too low, the number of non-recrystallized regions increases and the molding processability decreases, so the annealing temperature is limited to 810 ° C. or higher. Preferably it is 825 ° C or more. Since the recrystallization behavior changes depending on the selected component system and the rolling reduction before annealing, it is necessary to determine an appropriate annealing temperature within the above temperature range in order to stably secure a refined structure. preferable.
• the influence of the annealing time is relatively small, and recrystallization proceeds in a short time, so the lower limit of the annealing time is not particularly limited. What is necessary is just to implement on general manufacturing conditions, and what is necessary is just to hold
• Example 1 For chemical compositions A to I shown in Table 1, 30 kg test dissolution was performed. The setting concept of each alloy is as follows. In the following table, the underline indicates outside the scope of the present invention. The chemical composition “-” indicates that inclusion is not intended.
• Alloy A invention example, an example of a preferred form of the present invention.
• Alloy B Invention example, within the scope of the present invention, the Md30 value is increased by lowering the C content.
• Alloy C Inventive example, within the scope of the present invention, the Md30 value is lowered by increasing the C content.
• Alloy D Comparative example, a general SUS304 component system in which the C content and Md30 value are outside the scope of the present invention.
• Alloy E Comparative example, alloy D with reduced Cu and Mo contents and Md30 value within the scope of the present invention. C is out of range.
• Alloy F Comparative example, general SUS304L component system. Ni amount and Md30 value are outside the scope of the present invention.
• Alloy G Comparative example, the chemical composition is excessively reduced, and the Md30 value exceeds the range of the present invention.
• Alloy H Comparative example, SUS301L system proven as a fine-grained material. Low Cr and Ni contents are outside the scope of the present invention.
• Alloy I Comparative example, the content of Cr and Ni was too high, and the Md30 value was below the range of the present invention.
• Alloys A to I were melted in a high frequency melting furnace and statically cast into an ingot to obtain an ingot (60 mm ⁇ 200 mm ⁇ 340 mm) of about 30 kg. After the surface of the ingot was carefully treated by mechanical cutting, it was heated to 1150 ° C. and rolled to a thickness of 6 mm by hot rolling. After hot rolling, annealing was performed by holding at 1130 ° C. for 4 minutes, and the thickness of the plate was adjusted to 5 mm while removing the oxide scale on the surface by mechanical grinding. Thereafter, it was cold-rolled to 2 mm with a cold rolling mill to produce 6 cold-rolled steel sheets each exceeding 2 mm ⁇ 180 mm ⁇ 1000 mm and heated to 1100 ° C. in an Ax gas atmosphere (75% hydrogen—25% nitrogen). Annealed by holding for 2 minutes.
• Ax gas atmosphere 75% hydrogen—25% nitrogen
• test piece thus rolled was heat-treated by holding it at temperatures of 800 ° C., 820 ° C., 870 ° C., 920 ° C., and 960 ° C. for 30 seconds in an Ax gas atmosphere.
• test piece after the heat treatment was cut in a direction perpendicular to the rolling, and the average crystal grain size was measured by observing the cross section with an optical microscope.
• Alloy H alone has a particle size of 5 ⁇ m or less even when the rolling reduction is 60%, and it was reconfirmed that it is a component system suitable for refinement.
• alloys A, B, C, E, G, and H are selected and cold-rolled at a rolling reduction exceeding 65% (60 for alloy H). % Or more is acceptable).
• the final judgment of the rolling load was determined that the rolling load was excessive when the maximum current (mill current) consumed by the rolling motor during rolling exceeded 80A.
• Table 4 shows the survey results.
• Alloys A, B, C, E, G, and H were confirmed to have an average grain size of less than 5 ⁇ m when held at an annealing temperature of 820 ° C. to 920 ° C. for 30 seconds.
• Alloys A, B, G, and H were confirmed to have an average particle size of 3.0 ⁇ m or less when held for 30 seconds in the above annealing temperature range.
• the corrosion resistance was evaluated by measuring the pitting potential by the dynamic potential method according to JIS G 0577, using a test piece annealed at 920 ° C. after cold rolling at a rolling reduction of 75%.
• the evaluation was performed based on Vc′100, and it was determined that 300 mV or more passed on the basis of the saturated calomel electrode, and less than that was rejected.
• the alloy A was at a pass level, but the alloy H having a low Cr and Ni content was rejected.
• the test piece annealed at 870 ° C. for 30 seconds was confirmed to have a clear etching process with a rectangular shape according to the resist pattern, and was judged to have no problem as a stainless steel plate for precision processing.
• the sample annealed at 800 ° C. for 3600 seconds it was confirmed that the etching processed part was inferior in linearity, and the shape of the processed hole varied from pattern to pattern, and used as a stainless steel plate for precision processing. I decided I could't.
• the measurement result of the slit opening width is that the average value is 102 ⁇ m and the standard deviation is 3 ⁇ m (2.9% with respect to the average value) in the specimen annealed at 870 ° C. for 30 seconds.
• the specimens annealed at 800 ° C for 3600 seconds have a large variation of 104 ⁇ m in average value and 7 ⁇ m in standard deviation (6.7% of the average value), which is not suitable as a material for precision processing. Was confirmed.
• the cause of the deterioration of the linearity of the etched portion is considered to be due to the poor adhesion between the stainless steel plate and the photoresist.
• the cause of the variation in the shape of the processing hole for each pattern is thought to be due to the difference in the amount of dissolution depending on the location because the activation time at the initial stage of etching processing was different due to the presence of a strong coating layer. It is done.
• Alloy J Inventive example, an example of a preferred embodiment of the present invention, which corresponds to alloy A in laboratory tests.
• Alloy K Comparative example, a general SUS304 component system, the amount of C and the Md30 value are out of the scope of the present invention, and correspond to the laboratory test alloy D.
• Alloy L Comparative example, Cu and Mo are reduced from alloy D, and Md30 value is within the range of the present invention.
• C is out of range chemical composition and corresponds to alloy E in the laboratory test.
• Alloy M Comparative example, general SUS304L component system.
• the amount of Ni and the Md30 value are chemical compositions outside the scope of the present invention and correspond to laboratory test alloy F.
• the alloy of each component was melted in the atmosphere of 2.5 tons and continuously cast to obtain a continuously cast slab of 90 mm ⁇ 640 mm ⁇ 5400 mm.
• the surface was cared for by cutting to make it 85 mm ⁇ 640 mm ⁇ 4800 mm.
• the hot-rolled coil was subjected to air annealing at 1150 ° C. and then pickled with a mixed solution of hydrofluoric acid and nitric acid.
• first cold rolling After cold rolling, it was subjected to atmospheric annealing at 1150 ° C. and then pickled with a mixed solution of hydrofluoric acid and nitric acid.
• cold rolling (second cold rolling) was performed to 0.37 mmt using a reversible 6-stage cold rolling mill.
• the rolling reduction at this time is 82%.
• annealing heat treatment was performed at 850 ° C. for 48 seconds in a reducing Ax gas atmosphere (hydrogen 75% -nitrogen 25%).
• finish rolling to 0.15 mm was performed using a reversible 6-stage cold rolling mill.
• heat treatment was performed in the range of 600 to 800 ° C. to reduce residual stress.
• the average crystal grain size was measured by cutting out a small amount of sample after heat treatment in a bright annealing furnace and performing micro observation using an optical microscope in a cross section perpendicular to rolling.
• the manufactured rolled stainless steel plate was cut into 0.15 mm ⁇ 600 mm ⁇ 420 mm and subjected to etching. Etching is performed using a ferric chloride aqueous solution with a liquid temperature of 50 ° C. and a Baume degree of 43 degrees (about 40 mass% in mass percent), pressurized to 0.5 MPa, and sprayed with an etching solution only on one side for 100 seconds from a spray nozzle. And carried out. By measuring the surface roughness of the half-etched surface in which about half of the plate thickness was etched in this way, using a stylus type surface roughness meter, the center line average roughness (Ra) in the direction perpendicular to rolling was measured. The etching processability was evaluated. The measurement length was 4.0 mm, and the cut-off value for removing waviness was 0.80 mm.
• Table 7 shows the number of rolling passes in the second cold rolling in each alloy, the value obtained by dividing the total rolling reduction (82%) by the number of rolling passes, the average crystal grain size after bright annealing, and measurement after finish rolling.
• the centerline average roughness (Ra) of the half-etched surface and the overall judgment result are shown.
• the intended cold rolling with a rolling rate of 82% was carried out for all alloys, but the number of passes and the rolling load at that time varied depending on the alloy.
• the final 4 passes of Alloy K and the final 5 passes of Alloy L are rolled with a large tensile tension and rolling load, but the rolling rate per pass is less than 10%.
• the rolling load is not only high, but the product shape after rolling is apt to be deteriorated, and rolling under a condition of a large load and a low pressure reduction rate is unavoidable.
• alloys J and L the average crystal grain size after grain refinement annealing using a bright annealing furnace was 3.0 ⁇ m or less for alloys J and L. Alloys K and M are also refined to 10 ⁇ m or less by carrying out the large rolling and low-temperature heat treatment, but they are not 5.0 ⁇ m or less, which is the object of the present invention.
• the center line average roughness of the half-etched surface after half-etching in the final product is confirmed to be smoother than that of other alloys in alloys J and L, 0.28 ⁇ m and 0.32 ⁇ m, respectively. .
• alloys K and L are inferior in rolling productivity, and alloys K and M cannot have an average crystal grain size of 5 ⁇ m or less, and as a comprehensive judgment, only alloy J is superior. It was.

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